Thanks for the response Robert!
MV
Robert Story wrote:
On Tue, 09 Aug 2005 14:30:20 -0400 Mike wrote:
MV> That is, for every iteration through the table rows, the entire row is
MV> copied into the agent using snmp_set_var_value; and the entire table is
MV> iterated over before the 'handler' method is called and the requested
MV> variable is returned.
MV> So, my questions are:
MV> 1) why is this table reconstruction necessary for every GETNEXT? (I am
MV> assuming it is because the net-snmp core agent needs a snapshot of the
MV> table in order to select the right column / row to return; and it makes
MV> no assumptions about the table state between GETNEXT calls.)
Yep. It's meant to deal with unsorted data, and for unsorted data the only
way to find the 'next' object is to look at all the objects. Caching can
mitigate this.
MV> For small tables this is no big deal, but we are going to implement a
MV> table with around 20 columns, and there are potentially hundreds of
MV> rows: all this copying seems really expensive.
Later versions should be more efficient with regards to columns, so the number
of columns is irrelevant.
MV> 2) Is this how the old UCD API worked? Does the new way solve any
MV> errors? Will using the old UCD API be more efficient for large tables?
No, the old way passed the OID to the handler, which had to deal with get-next
processing. That's tricky for get-next, and people often didn't understand it,
or did it wrong.
Note that there are many new methods that use the new API, iterator is just
one.
MV> 3) Is the mib2c 'mib2c.array-user.conf' a more efficient interface for
MV> large tables, and are there examples of this pattern?
Array user assumes the entire table is kept in memory, and is kept sorted. If
that fits your model, it will be much more efficient.
MV> 4) Any recommendations for implementing large tables efficiently?
That depends on the table, where it gets its data, and who 'owns' the data.
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mike Varley -= SOMA Networks =-
[EMAIL PROTECTED] 416-348-1578
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